gradebook.cpp

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// Fig. 4.13: GradeBook.cpp
// Member-function definitions for class GradeBook that solves the 
// class average program with sentinel-controlled repetition.
#include <iostream>
using std::cout;
using std::cin;
using std::endl;
using std::fixed; // ensures that decimal point is displayed

#include <iomanip> // parameterized stream manipulators  
using std::setprecision; // sets numeric output precision

// include definition of class GradeBook from GradeBook.h
#include "GradeBook.h"

// constructor initializes courseName with string supplied as argument
GradeBook::GradeBook( string name )
{
   setCourseName( name ); // validate and store courseName
} // end GradeBook constructor

// function to set the course name;
// ensures that the course name has at most 25 characters
void GradeBook::setCourseName( string name )
{
   if ( name.length() <= 25 ) // if name has 25 or fewer characters
      courseName = name; // store the course name in the object
   else // if name is longer than 25 characters
   { // set courseName to first 25 characters of parameter name
      courseName = name.substr( 0, 25 ); // select first 25 characters
      cout << "Name \"" << name << "\" exceeds maximum length (25).\n"
         << "Limiting courseName to first 25 characters.\n" << endl;
   } // end if...else
} // end function setCourseName

// function to retrieve the course name
string GradeBook::getCourseName()
{
   return courseName;
} // end function getCourseName

// display a welcome message to the GradeBook user
void GradeBook::displayMessage()
{
   cout << "Welcome to the grade book for\n" << getCourseName() << "!\n" 
      << endl;
} // end function displayMessage

// determine class average based on 10 grades entered by user
void GradeBook::determineClassAverage()
{
   int total; // sum of grades entered by user
   int gradeCounter; // number of grades entered
   int grade; // grade value
   double average; // number with decimal point for average

   // initialization phase
   total = 0; // initialize total
   gradeCounter = 0; // initialize loop counter

   // processing phase
   // prompt for input and read grade from user  
   cout << "Enter grade or -1 to quit: ";        
   cin >> grade; // input grade or sentinel value

   // loop until sentinel value read from user   
   while ( grade != -1 ) // while grade is not -1
   {                  
      total = total + grade; // add grade to total
      gradeCounter = gradeCounter + 1; // increment counter
      
      // prompt for input and read next grade from user
      cout << "Enter grade or -1 to quit: ";           
      cin >> grade; // input grade or sentinel value   
   } // end while

   // termination phase
   if ( gradeCounter != 0 ) // if user entered at least one grade...
   {
      // calculate average of all grades entered              
      average = static_cast< double >( total ) / gradeCounter;
      
      // display total and average (with two digits of precision)
      cout << "\nTotal of all " << gradeCounter << " grades entered is " 
         << total << endl;
      cout << "Class average is " << setprecision( 2 ) << fixed << average 
         << endl;
   } // end if
   else // no grades were entered, so output appropriate message
      cout << "No grades were entered" << endl;
} // end function determineClassAverage

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